(a) Field of the Invention
The present invention relates to an organic silicate polymer having superior mechanical property and low dielectric property, and more particularly to a method for preparing organic silicate polymer having superior mechanical property and low dielectric property, an organic silicate polymer prepared therefrom, a composition for forming insulation film of semiconductor devices, a method for preparing insulation film using the composition, and a semiconductor device comprising the insulation film.
(b) Description of the Related Art
As the degree of integrity of semiconductor devices has been increased, linewidth of conducting wires that connect the devices has been rapidly reduced. In the year 2003, it is expected that high-density devices using 0.1 μm will be developed.
Generally, the speed of semiconductor devices is proportional to switching rate of transistors and signal transfer rate. The signal transfer rate is determined by the RC (Resistance-Capacitance) delay, which is the product of resistance of a wiring material and capacitance of an insulation film in semiconductor devices. With the increase of degree of integrity of semiconductor devices, gaps between metal wires inside the devices become narrow. Also, while thickness of the metal wires becomes small, their lengths increases rapidly. And, the speed of high-density chips is mainly determined by the RC delay rather than by the switching rate. Accordingly, High-speed chips employ conductors having low resistance and insulators having low dielectric constant. In addition, the chips employing the materials having low dielectric constant prevent power consumption and cross-talk between the metal wires.
Recently, International Business Machines Corporation has released semiconductor products using copper wires instead of conventional aluminum wires. The new products offer more than 20% of speed improvement. Semiconductor devices using the materials having low dielectric constant, however, are not on the market, due to the lack of suitable materials.
Most of the conventional semiconductor devices like ICs and LSIs use SiO2as insulators. The dielectric constant of SiO2 is 4.0. And, fluorine-doped silicate (F—SiO2), which has lower dielectric constant, is used for some devices. However, if the fluorine content of F—SiO2 is larger than 6%, it becomes thermally unstable. Therefore, it is difficult to lower the dielectric constant of F—SiO2 below 3.5. In order to solve this problem, many organic and inorganic polymers thermally stable and having low polarity have been proposed.
For organic polymers having low dielectric constant, polyimide resin, polyarylene ether resin and resin containing aromatic hydrocarbon or perfluorocyclobutane are known. These resins may or may not contain fluorine. While most of these organic polymers have dielectric constant lower than 3.0, they have poor elasticity at high temperature due to low glass transition temperature, and very high linear expansion coefficients. In particular, these problems are more severe in the fluorine-containing organic polymers. Because high temperature of 200° C. to 450° C. is associated with semiconductor manufacturing and packaging processes, organic polymers having poor thermal stability and elasticity and high linear expansion coefficient may deteriorate reliability of semiconductor devices or circuit boards.
Recently, organic silicate polymers using alkoxy silanes have been developed to solve the thermal stability problem. The organic silicate polymers are formed by hydrolyzing, condensing and hardening organic silanes. The organic silicate polymers, for example, methylsilsesquioxane and hydrosilsesquioxane have rather low dielectric constant below 3.0 and are thermally stable at 450° C. However, these polysilsesquioxanes are vulnerable to cracks if the thickness of these polymers is larger than 1 μm due to the condensation stress during the hardening process. Also, while these polysilsesquioxanes have relatively higher mechanical strength than that of organic polymers, additional processing to reduce the dielectric constant below 2.5 lowers the mechanic property.
Therefore, organic silicate having low dielectric constant and superior mechanic property is needed.